06-26-2001 Agenda Packet - Laserfiche WebLink

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INNES OTA AG DEVELOPMENT DIVISION MINNESOTA DEPARTMENT OF AGRICULTURE P+E ST : E*P*O+R+T MPR 14-00 Gene Hueoson Commissioner Aueust 25. 2000 Soybeans .after last weeks report of Aphis glycines(soybean aphid)in Wisconsin,we began a special survey to determine if the aphid was present in Minnesota—and if so,to map its distribution. Since August 18,we have found aphids resembling A.glycines in 6 Minnesota Counties: Houston,Winona,Wabasha,Goodhue, Fillmore and Olmsted. However,while ~I`, these aphids resemble.4.glycines they l T s have not been yet been confirmed as 1 such. The greatest aphid abundance is in Houston and Winona Counties ;= t where every field checked has �. contained aphids. Wabasha County G 4b of soybean ptarrts rtiEh aphids 1 �f has also had aphids found in every 0 . field,however only 2 fields have been visited. Goodhue,Fillmore and <, So Olmsted Counties have produced fields • _ j with and without aphids. In addition ` •1 '" ;r�_ y 00 to these counties.University of + +' Minnesota researchers have found aphids resembling A.glycines in f.. �4 . Ramsey and Dakota Counties. Finally, y•"• • "; just today a specimen came in from ,, �'• - r m Meeker County that resembles the '•, .« soybean aphid. All other counties remain negative for aphids of any kind in soybeans(see map). Fields are •„ k;. ,�•,+, checked for aphids by inspecting 10 '� '• whole plants,each separated by at least '..��,,, *+�;,,.t.• t 10 m. The infestation is quantified by ( •� '; expressing the number of plants infested per 10 checked as a percentage "• '. t l w"*�"�, for the field. In addition.the , abundance of aphids on each plant is �'t' , t rated as • Light=aphids present but rare • Moderate=aphids easily found but not abundant • Heavy=plant inundated with aphids 1i Aphid abundance on all infested plants has been rated as light. In fact,we are regularly finding only 1-2 aphids on l leaf per plant. This low abundance may be partially due to the time of year as soybeans are reaching maturity and ---�j soybean aphids'would be switching to their primary host.European buckthom—an exotic forest weed.%Observations made by University of Minnesota Entomologist Ken Ostlie"of ar aphid infested field in Wisconsin indicate that the damage caused to plants may be distinctive. Leaf discoloration is found that resembles a potassium deficiency where the leaf surface along the veins remains green but the rest of the leaf turns veilow. We spotted these symptoms in relatively few fields during our survey. Some fields where these symptoms were found contained aphids,others did not. This may indicate that aphid populations were more abundant cariier in the season. The picture below was taken in a field in Goodhue Counrv—aphids were found on this plant. However,as a whole this field looked excellent and most fields where aphids were found were heaithv and showed no observable damage. Considering the maturity of the crop and the low abundance of aphids.treatment does not need to be considered for aphids in soybeans this season.